Heat assisted magnetic recording (HAMR) generally refers to the concept of locally heating a recording media to reduce the coercivity of the media so that an applied magnetic writing field can more easily direct the magnetization of the media during the temporary magnetic softening of the media caused by the heat source. A tightly confined, high power laser light spot can be used to heat a portion of the recording media. Then the heated portion is subjected to a magnetic field that sets the direction of magnetization of the heated portion. With HAMR, the coercivity of the media at ambient temperature can be much higher than the coercivity during recording, thereby enabling stability of the recorded bits at much higher storage densities and with much smaller bit cells.
A significant consideration for heat assisted magnetic recording is the location of a laser diode that is used as the optical power source. One current design integrates a laser diode into the trailing edge of the slider and uses a waveguide coupler to guide the laser to the near field transducer using a combination of light-positioning elements such as solid immersion minors (SIMs) and/or channel waveguides.
Integrating laser diodes into a HAMR slider have been described using methods such as solder self alignment and optical couplers. In certain embodiments, a recessed cavity is created on the trailing edge of the read/write head for the laser diode to be precisely attached such that the output of the laser diode interfaces with the correct optical waveguide/recording head layers. One key challenge in the processing of laser-in-slider type read/write heads relates to providing a protection mechanism between the laser diode output and outside particle and chemical contamination. This is particularly challenging when the diode is in a cavity and the geometrical gaps between the diode and cavity are not constant. The gap between a laser diode and an optical coupler is typically required to be less than 1 micron while the gaps around other areas of the laser in a cavity may be several to tens of microns to allow for effective assembly space. This creates a challenge in universally sealing the interfaces around a laser diode.